All About the Bass 2024 - Susanne Tanner (MARE)

"All About the Bass" was a one day symposium on 8th July 2024 hosted by the University of Essex showcasing the latest in European sea bass science and providing a forum for scientists, anglers and policymakers to discuss ways that we could work together to improve bass monitoring and management (www.tinyurl.com/BassEvent). #BassConf

Susanne's talk: Not so much a sea bass: Divergent freshwater incursions of European sea bass

The existence of distinct migratory and resident individuals within fish populations has been reported increasingly. This phenomenon referred to as partial migration entails a trade-off between multiple factors and can evolve and be maintained either when different life-history strategies produce the same lifetime fitness or because of conditional strategies dependent on individuals. Several species within the family of the temperate basses (Moronidae) exhibit contingents or subpopulations, that have different movement behaviors along the marine-freshwater gradient. European sea bass (Dicentrarchus labrax) is a marine migrant, with juveniles commonly using estuaries and even freshwater environments. Although, the co-occurrence of residents and seasonal migrants has been reported in marine environments, there are no reports of adult seabass using freshwater habitats. Here, we document the occurrence of adult sea bass in freshwater environments in the Tagus River, Portugal (~150 km upstream from river mouth and 80 from tidal influence) using individuals captured by anglers and data obtained by interviewing commercial and recreational fishers regarding the spatio-temporal patterns of freshwater use of adult sea bass.

Susanne's Biography:
Dr Susanne Tanner is a senior researcher at the Marine and Environmental Sciences Centre (MARE) and an adjunct Assistant Professor at the Faculty of Sciences, University of Lisbon, Portugal. Her research focuses on 1) estimating fish population structure and connectivity, mainly using chemical markers as well as by integrating different natural markers and modelling approaches; and 2) assessing the impacts of climate change and fishing on growth variability, fish population and marine ecosystem productivity. She is part of a multidisciplinary team investigating movements of adult European seabass into fully freshwater environments, a movement behavior recently described for the Tagus River (Almeida et al. 2023). By combining acoustic telemetry, otolith chemistry and genetics the team aims to better understand the diversity of seabass freshwater incursions and its importance for the population.